Motor,pump,and blower system for oil burner



May 26, 1970 K. G. sJoTUN ETAL MOTOR, PUMP, AND BLOWER SYSTEM FOR OIL BURNER Filed Feb. l2, 1968 United States Parent O 3,514,241 MOTOR, PUMP, AND BLOWER SYSTEM FOR OIL BURNER Kyrre Guttorm Sjotun, Nordborg, and Leif Viggo Sturlason, Sonderborg, Denmark, assignors to Danfoss A/ S, Nordborg, Denmark, a company of Denmark Filed Feb. 12, 1968, Ser. No. 704,677 Claims priority, applictign (grmany, Feb. 18, 1967,

Int. Cl. F2311 5/24 U.S. Cl. 431-30 5 Claims ABSTRACT 0F THE DISCLOSURE An oil burner system in which a fuel oil pump and the air blower are independently driven by a common motor having a single stator and two independently driven rotors. One rotor is connected to the pump and the other to the air blower so that the intertia of the pump drive is reduced and it comes to a stop quicker. The rotor for driving the pump is disposed in an oil-filled compartment so that it is damped. When the motor is deenergized the pump stops relatively quickly and the blower continues to blow air to ensure burning of all oil supplied from the burner and avoid coking.

This invention relates generally to oil burners and more particularly to an oil burner system comprising a burner nozzle motor, oil pump and blower.

The usual oil burner system has a motor which drives both the fuel oil pump and the air-supply source, for example a blower. When the motor is turned off it continues to rotate due to the inertia of the assembly connected thereto. Thus fuel oil continues t-o be fed by the fuel oil pump at a diminishing pressure for a relatively long period of time. This oil tends to drip from the nozzle as the pressure is reduced and the nozzle and areas on which the oil impinges become coked. It has been the common practice to insert complicated cut-off valves between the pump and the nozzle for precluding this kind of drippage. The cut-off valves responded to the oil pressure, for example, and effect closure rapidly as soon as the oil pressure drops below a predetermined level.

It is a principal object of the present invention to provide an oil burner system in which the problem of dripping oil, when the oil pump motor is turned off, is eliminated.

Another object of the present invention is to provide an oil burner system in which the avoidance of dripping oil once the oil pump is turned off is effected by simple means.

In the oil burner system according to the invention an oil burner is supplied fuel oil by a fuel oil pump and a blower provides air for combustion of the oil. A common motor drives the oil pump and the air blower independently of each other. The motor comprises a single stator and has a rotor which is divided into two coaxial parts one of which drives the pump and the other the blower independently of each other.

A feature of the construction is that the inertia of the rotating parts associated with the pump is considerably reduced. Thus when the motor is turned olf it comes to a stop more rapidly than heretofore in motors in which the pump and air supply source are mounted to be jointly driven from a common rotor. Thus when the motor is 3,514,241 Patented May 26, 1970 turned off less fuel oil is supplied and this avoids the dripping of oil that takes place if the pump does not stop rapidly. Moreover, the air blower is not braked or damped by the pump so that it runs freely for a considerably longer time and therefore provides continuously a ow of air so that any oil that would tend to drip is consumed and blown away from the nozzle so that coking is not possible. The use of independent drive for the oil pump and blower means that upon switching off the apparatus the oil burner system need not have a cut-off valve or if it is desired to use one it can be of a simple design.

An advantage of the invention is that there is no appreciable extra cost involved in the construction of a motor having a split rotor or two rotor parts independently driven of each other by a common stator winding. The stator has its usual or normal winding and the two rotors are mounted coaxially.

A fluid-tight partition is disposed between the two rotors Within the stator and motor housing and defines a compartment in which the rotor driving the pump is disposed. Oil from the pump is delivered into this compartment during operation so that the rotor driving the pump is damped or braked so that the pump comes to a stop relatively quickly after the motor has been switched off. This type of construction avoids the need of a stuing box between the pump and the oil-filled compartment of the motor so that the pump shaft rotates with considerably less friction. The reduced friction increases performance characteristics which readily make up for the losses caused by the damping oil in the oil-filled compartment. Moreover, the oil in this compartment effects cooling of the stator and the rotor within the compartment.

In order to construct the oil-filled compartment the partition within the stator consists of a cup-shaped member in which the rotor part that drives the blower is enclosed. The bottom of the cup-shaped member forms a partition defining with the stator and housing a compartment which is oil-filled and in which the stator and the rotor for the pump are disposed internally of the motor housing. Thus all the motor parts, except the rotor associated with the blower, are cooled by oil provided from the pump and which is returned to the suction side of the pump.

A simple arrangement is possible if the cup-shaped member is disposed with the mouth or opened end thereof circumferentially of a bearing -for the blower rotor and has a rim on its mouth abutting against an end wall of a part of the motor housing. A simple seal between the inner circumference of the cup-shaped member and the outer periphery of the bearing suffices to seal the blower rotor internally thereof and define a fluid-type compartment for the remainder of the motor and in which oil can be provided from the pump and returned thereo. The oil within the oil-filled compartment assists in applying pressure to the cup-shaped member tending to hold it in position.

In order to particularly maintain the motor cooled in extensive operation the oil-filled compartment in the motor is delivered from the pressure side of the pump through a pressure-regulating valve and/or cut-off valve. As soon as the motor has been turned on and reaches speed the oil under pressure is circulated through the oil-filled compartment so that a good cooling effect is achieved during operation. The cut-off valve employed in conjunction with the invention comprises a spring-loaded pressed regulator valve of known type having an extension which directly 3 closes the nozzle or burner supply line. Other known pressure-regulating valves can perform the cut-olf function.

The motor and pump construction is such that the motor shaft connected to one of the rotors constitutes the pump shaft and has a bearing insert for the pump rotor of a diameter that is equal to or greater than that of the rotor itself. The pump shaft bearing also acts as a bearing for the rotor and the rotor is mounted on an extension of the pump shaft, e.g. by being shrunk thereon or mechanically secured in some other way. The pump and its associated rotor parts can thus be replaced as a unit.

Other features and advantages of the oil burner system in accordance with the present invention will be better understood as described in the following specication and appended claims, in conjunction with the following drawings in which: I

FIG. 1 is an elevation sectional View of a motor drive for the oil burner system in accordance with the invention;

FIG. 2 is a diagram o f an oil burner system according to the invention; and

FIG. 3 is a fragmentary section view of a pressure-regulating and cut-off valve used in an oil burner system in accordance with the invention.

As illustrated in the drawing a motor drive for an oil burner system as hereinafter constructed is shown in FIG. l and comprises a stator l1 with a winding 2 held in two half-shells 3, -4 of a motor housing. Within the stator is mounted for rotation a first rotor or rotor part `5 driving a shaft 6 which rotationally drives an air blower 7. A second rotor or rotor part 8 independent of the other rotor is mounted coaxially with the other rotor and rotatably drives a shaft 9 connected to a pump 10. The shaft 6 is mounted coaxial with a bearing bushing 11 and extends through an end wall of the half-shell 3 of the housing. The shaft 6 is secured against axial displacement by means of a locking device 12. The pump shaft 9 is mounted in two bearing bushings 13, 14 coaxially disposed in a pump housing 15 which is secured in a central opening in the housing half-shell 4 by a ring 16 and circumferentially disposed screws 17.

The two rotor parts 5, 8 are separated from each other by a fluid-tight partition 18. The partition is part of a cupshaped member 19 having the walls of the cup part of the member bear against the stator 1 and the inner surfaces about the mouth of the cup-shaped member bear against the circumference of an annular part 21 of the housing. This housing part has an annular recess in which is disposed a seal ring 20 effecting a seal between the inner surfaces of the mouth of the cup-shaped member and the portion 21 of the housing. In this manner an oil chamber or compartment 22 is dened by the parts 3, 4, 15, 16 and 19. This compartment or chamber is oil-filled during operation as hereinafter explained.

The overall burner nozzle system is illustrated diagrammatically in FIG. 2. The pump 10 is connected to a suction line 23 which takes a suction from an oil sump 24 and delivers it to a pressure discharge line or passage 25 to a valve arrangement 26 which comprises a pressureregulating valve and a cut-olf valve hereinafter described. When the cut-off valve is open oil under pressure flows to a nozzle 27 which delivers oil to be burned into a combustion chamber of the burner, not shown. The excess oil which is not required Hows through a return passage 28 in communication with the chamber 22 and back through an outlet to the sump 24 or to the suction side of the pump as illustrated. Those skilled in the art will understand that the pump 10, the valve unit 26 and the associated lines or passages may be constructed as one unit. The pump housing 15 can, for example, house the valve system 26 and the passages, for example the passages 25 and 28.

The construction of the motor-pump-blower unit shown in FIG. 1 is readily accomplished. The housing parts 3, 4 are mounted and connected to the stator 1. Then the shaft 6 together with its associated rotor 5 are moved axially through the right hand opening in the housing and are secured against axial displacement by means of the securing device 12. The cup-shaped member 19 is then inserted likewise from the righthand side and is disposed in the position illustrated in FIG. 2. After this it is only necessary to insert the pump and rotor assembly unit consisting of the parts 8-10 and 15-16 and to tix them by means of the ring and screws 17. If the pump housing -15 contains all of the necessary connecting passages or lines the oil chamber 22 is also connected into the oil recirculating circuit when this fitting in position takes place. Axially extending connecting passages, for example an axial passage 29 in the rotor part 8, provide for oil entering into the chamber reaching all the parts to be cooled.

A pressure-regulating and cut-olf valve 36, FIG. 3, may be mounted in the pump housing 15 for carrying out pressure regulation and cut-off of fuel oil supply to the nozzle 27 when the fuel oil pump is stopped. A bore 37 is provided in the housing 15 and has at one end thereof a threaded plug 38 which comprises a nozzle supply outlet 39 and a valve seat 40 for the cut-off valve. At the other end of the valve bore is provided a threaded bushing hollow cap 41 having a closed end and movable axially to adjust a spring `42 housed internally thereof. The spring biases valve element 43 of a pressure-regulating valve, which is axially guided in a bushing 44 acting in the manner of a guide slide, toward a seated position. The valve element y43 has an axial extension 45 which forms the cut-olf valve.

A passageway 46 is in communication with the pressure line or passage 25 and another passage 47 corresponds to the return line or passage 28. Thus when a certain pressure is applied through the inlet passage 46 of the valve unseats against the action of the spring 42 and at a reduced pressure after the pump is stopped the cut-olf valve extension 45 will seat on the valve seat 40 cutting off supply of fuel oil to the nozzle. During the time that the valve, however, is seated cooling oil flow is permitted through the compartment 22 through passageway 47 as,

heretofore described.

1n a specific construction of a unit in accordance with the invention a two-pole single phase motor was used. The two rotor parts 5, 8 reached a speed of approximately 2900 r.p.m. When the motor was turned olf the pump came to a stop rapidly and the blower still continued to turn at 2700 r.p.m. The result was that such a strong current of air was supplied to the fuel nozzle that full combustion was maintained until no further oil was -being fed to the nozzle and the air flow continued while no oil was forced out or dripped from the blocked or closed nozzle.

While a preferred embodiment of the invention has been shown and described it will be understood that many modicatons and changes can be made within the true spirit and scope of the invention.

What we claim and desire to be secured by Letters Patent is:

1. In a pump and blower system for oil burners, in combination with a fuel oil nozzle, a fuel oil supply pump for the nozzle and a driven air-supply source supplying in operation air under pressure to effect combustion of fuel oil supplied by said nozzle, the improvement which comprises a motor for driving the oil pump and said air-supply source independently of each other, said motor having two independently driven rotors, for each rotor an independent shaft, said motor comprising a single stator for said two rotors, and means defining a compartment for receiving oil from said pump such that said stator is bathed by said oil and cooled thereby.

2. In a pump and blower system according to claim 1, in which said means defining said compartment comprises a cup-shaped member interiorly of said stator, and said rotor connected to said blower disposed interorly of said cup-shaped member.

3. In a pump and blower system according to claim 1, including a bearing insert for one of said rotors, said bearing insert having a diameter at least equal to a diameter corresponding with a diameter of said one of the rotors.

4. In a pump and blower system according to claim 3, in which said bearing insert comprises a bearing for said pump and said one rotor, and one of said shafts is connected to said rotor and comprises a pump shaft.

5. In a pump and blower system according to claim 1, including valve means to cuto supply of fuel oil to said nozzle when said motor drive is deenergized and effective to continue to circulate fuel oil through said compartment when said supply of fuel oil to said nozzle is cut-off.

References Cited UNITED STATES PATENTS 1,780,337 11/1930 Canton 2SC-S8 1,985,934 1/1935 Logan 431--89 EDWARD G. FAVORS, Primary Examiner U.S. Cl. X.R. 10S-6 

